Hi,

①T208 is a UPS expansion board, please power to the Nano via T208. Do not reverse power supply!!

②The T208 board has a built-in protection circuit, you can also use a 18650 battery with a protection circuit, but please pay attention to the size of the battery, because many batteries with a protection circuit are larger in size. To avoid using the wrong size battery, we recommend using a battery without a protection circuit.